WEDNESDAY, July 17 (HealthDay News) -- The rate of addiction to cigarettes is extremely high among Americans who are homeless, experts say, and this population needs better access to methods of helping them quit.

There are up to 3.5 million homeless people in the United States and three-quarters of them smoke cigarettes, "a rate that's four times higher than in the general population," say doctors writing in the July 18 issue of the New England Journal of Medicine.

As a consequence, "homeless people seem to be dying of smoking-related causes at high rates," said Dr. Travis Baggett, an instructor of medicine at Harvard University. Baggett has been tracking the health problems of 28,000 homeless people in Boston for more than six years as part of his involvement with the Boston Health Care for the Homeless Program.

"Cancer is the second leading cause of death overall [for homeless people] and heart disease is the third leading cause of death overall," he said. "The leading type of cancer death was lung cancer."

Treatment of those diseases is expensive and paid for by taxpayer-funded programs, which gives all Americans an economic incentive to tackle the issue.

But Baggett and other experts say there's also a moral imperative to help homeless smokers quit.

"They've sadly been a target of the tobacco industry," Cheryl Healton, president and CEO of Legacy, a national nonprofit that promotes public health, pointed out. "Over time, the tobacco epidemic has become more and more concentrated among those least in a position to pay for cessation services and access health care," she said.

The article highlights past "outreach" efforts by the tobacco industry to target homeless people, including donations of cigarettes and branded blankets to homeless shelters.

R. J. Reynolds even had a callously named program in the 1990s called Project SCUM, for Sub-Culture Urban Marketing, to target "street people" and those with "alternative lifestyles" in San Francisco.

Documents related to project SCUM were uncovered by lawsuits against tobacco companies, and they are currently archived and made publicly available at the Legacy Tobacco Documents Library at the University of California, San Francisco.

The tobacco company now disavows the effort. "This inappropriate and offensive document presented an idea for marketing cigarettes to adult smokers who chose alternative lifestyles," said David Howard, senior director of communications for Reynolds American Services, in an email to HealthDay.

"When R.J. Reynolds became aware of this document, the company saw that it used language that was unacceptable, inappropriate, offensive and insulting, and the company publicly apologized. The document did not reflect the opinions, policies or practices of the company -- in fact, it could not have been more opposed to R.J. Reynolds' operating philosophy and practices," Howard said.

Most importantly, he said, "The proposal was never pursued or put into action."

But Healton contends that that was untrue.

"Not only was it implemented. There are internal documents that show sign-off on the campaign all the way to the top," she said.

By the time it was deployed on the streets, management had given it a name change, to "Project Sourdough."

"There's actually a document demonstrating the success of the campaign. They boosted smoking rates among both people living on the street and gay people," Healton said.

And according to Baggett, once a homeless person starts smoking, health care workers often don't view quitting smoking as their top priority. That's because homeless people may appear to have more urgent needs -- namely finding food and shelter.

"A chronic problem like smoking seems like it maybe shouldn't be the most pressing issue at the forefront of what we're tackling with them. I can certainly understand that," said Baggett, who admits that he didn't discuss smoking with his homeless patients for a long time.

However, he said, "as you take a step back and look at the public health implications and public health impact, what we're finding is difficult to ignore."

And Baggett said that health care workers often make a mistake when they assume that people who are homeless don't want help to quit. "The vast majority of homeless people, just like any other type of patient we see, they want to be healthy. They want to feel better," he said.

"There's something that's reaffirming about addressing issues like exercise and smoking, even with people who are living in extreme circumstances because there's something normalizing and affirming about that," Baggett added.

What's more, Baggett said a strong case can be made for the idea that an addiction to tobacco, which is expensive, is a factor that may keep people from escaping the streets.

"It's not just a financial cost, it's also an opportunity cost, because [of] all the time that's spent getting money for cigarettes." he said. "It's probably contributing to keeping people in the cycle of poverty."